The invention relates generally to electrical system power control and, more particularly, to techniques (methods and devices) to cancel a user initiated power-off action.
Many older computer systems (e.g., personal computers and specialized workstations) employed large, stiff power switches that were typically recessed into the rear panel of the computer system""s enclosure. Because of this placement, it was often difficult for a user to physically operate the power switch. In this environment, user""s seldom inadvertently turned their computer system off.
Many new computer systems as well as many other types of electrical devices, however, use small momentary contact power switches located in a position easily accessible to users. For example, many current computer systems have small, easily activated power switches prominently located on the computer system""s enclosure""s front panel. This combination of a small and easily depressed switch makes inadvertent power down actions much more frequent. This may be particularly true for desktop units where the power switch is often on the system""s front panel. Inadvertent power down operations, in turn, can lead to a loss of data (e.g., if one or more files had not been saved prior to the power down operation) or an inconvenience to the user.
Thus, it would be beneficial to provide a power control mechanism that allows a user to recover from an unwanted power-down action.
In one embodiment the invention provides a method to manage power to a device. The method includes receiving a first power-off request signal, initiating a predetermined delay period, and canceling the first power-off request if a second power-off request signal is received before expiration of the predetermined delay period. In one embodiment the device is a computer processor. In another embodiment the device is a power supply relay or power supply. In yet another embodiment, the device may be a video cassette recorder.
In another embodiment, the invention provides a switch control circuit that includes a detector to detect a first activation of the switch, a delay circuit (coupled to the detector) to delay a power-off action for a predetermined period of time following detection of the first switch activation, and a cancel circuit to cancel the power-off action if the detector detects a second power switch activation during the predetermined period of time.